Beauty derived from functionalism.
Adjective form: "functionally-beautiful"
My friend who is an engineer, will stare at the following things, like one gazes at fine art: Wood-burning-stoves, Stirling-engines, Opticas, Orinithropters, Theremins, Brachistichrone-curves, and Derigibles; because they have a functional-beauty derived from the elegant way they achieve their goals.
Many "functionalist" buildings are not functionally-beautiful, because the designers often forego the shortest/quickest paths in favor of a cumbersome grid-like floorplan.